Periodontal Bacteria Linked to Alzheimer’s Amyloid
MedicalResearch.com Interview with:
ANGELA R. KAMER, DMD, MS, PhD
Periodontology and Implant Dentistry
MedicalResearch.com: What is the background for this study?
Response: The accumulation of amyloid β plaques and neurofibrillary pathology in the brain are pathognomonic to Alzheimer’s disease (AD). Brain amyloid deposition begins decades before cognitive dysfunction and is thought to be the first AD pathological feature followed by tau tangle accumulations and other pathologies.
The mechanisms by which brain amyloid develops are incompletely understood although inflammation and bacterial imbalances (known as dysbiosis) of the gut and oral cavity may be involved. Periodontal disease affecting more than 50% of elderly is an inflammatory, chronic condition characterized by periodontal tissue destruction and bacterial imbalances. Using PET studies, we showed previously that measures of periodontal destruction were associated with brain amyloid retention in the brain . In this study, we sought to investigate whether subgingival (under the gum line) bacteria associated with Alzheimer’s disease specific pathology, namely amyloidosis and tauopathy.
MedicalResearch.com: What are the main findings?
Response: In cognitively normal elderly, we showed that subgingival periodontal dysbiosis associated with reduced cerebrospinal fluid (CSF) Aβ42, but not with the CSF P-tau. CSF Aβ42 is a biomarker for brain amyloid and its reduced levels in the CSF reflect brain amyloidosis. We observed both periodontal associated bacteria increased as well as healthy bacteria decreased in the association with CSF amyloid levels. These results suggest that the subgingival imbalanced bacteria are important in Alzheimer’s disease pathology and not only one bacterium.
MedicalResearch.com: What should readers take away from your report?
Response: Gut dysbiosis has been found to be important in AD pathogenesis. Now, we find out that periodontal/oral dysbiosis may play a role in AD and its pathology. Periodontal disease is a preventable, treatable disease. Therefore, until more data is available, maintaining periodontal/oral health is of paramount importance. Good oral hygiene, frequent visits to the dentist, preventing and treating periodontal disease may have beneficial effects beyond the oral cavity.
MedicalResearch.com: What recommendations do you have for future research as a result of this work?
Response: Our study was a cross-sectional study and therefore causation cannot be determined. Larger cross-sectional studies to replicate our results and longitudinal studies to determine bacterial effects on brain amyloid progression would be recommended. Periodontal intervention studies are desirable to provide the needed “experimental evidence” that improving bacterial imbalances through periodontal treatment would prevent or even decrease the brain amyloid.
Kamer, AR, Pushalkar, S, Gulivindala, D, et al. Periodontal dysbiosis associates with reduced CSF Aβ42 in cognitively normal elderly. Alzheimer’s Dement. 2021; 13:e12172. https://doi.org/10.1002/dad2.12172
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